The smartphone-assisted sensing platform based on manganese dioxide nanozymes for the specific detection and degradation of hydroquinone

Hydroquinone (HQ) is a prevalent pollutant in aquatic environments, posing significant risks to ecosystems and human health. Practical methods for the simultaneous detection and degradation of HQ are essential. To address this requirement, a dual-mode detection and degradation strategy has been developed utilizing designed nanozymes (DM) consisting of a porous SiO₂ core and MnO₂ shell. Due to the catalytic activity of DM nanozymes, the three types of reactive oxygen species (ROS), singlet oxygen (¹O₂), superoxide anion (O₂^•-), and hydroxyl radical (•OH), were generated to induce the color transferring of 3,3',5,5'-tetramethylbenzidine (TMB) from colorless to blue form (oxTMB). During the reductive HQ-mediated oxTMB fading, the DM has significant selectivity towards HQ from isomers (catechol and resorcinol) due to the differing reductive reaction rates, with an excellent linear range of 0.2-45 μM with a detection limit as low as 0.11 μM. In addition, according to the color parameter changes in the sensing process, colorimeters and smartphones are utilized to achieve on-site and convenient HQ detection. Besides, the DM nanozyme can oxidatively decompose HQ without auxiliary equipment. We believe this research provides a powerful tool for detecting and removing HQ precisely.